"I commend them fully because because they’ve been pretending like there’s music playing when there’s not," she explains in the clip, pulling out some discreet personal headphones to show to the camera. "I have these in my ears. They’ve been dancing to a click track. It’s incredibly hard work.”

So basically, she keeps her music from leaking by...not playing it.

Elsewhere in the video, Swift and Sheeran discuss how the song came together, including Sheeran's "Fourth of July" lyric, which doubles as a reference to the 1989 film Born on the Fourth of July and a nod to the beginnings of his relationship with now-fiancé Cherry Seaborn. Apparently, Sheeran was at Swift's annual Fourth of July party in Rhode Island when Seaborn, an old friend of his from school, happened to be in the area. He invited her to stop by, and as Sheeran says, "here we are."

Watch Swift explain the click track around the 3:45-minute mark. The Reputation stadium tour launches May 8 in Glendale, Arizona.